The present invention relates to a multi-piece solid golf ball. More particularly, it relates to a multi-piece solid golf ball having very good shot feel, excellent durability and excellent flight performance.
In golf balls commercially selling, there are solid golf balls such as two-piece golf ball, three-piece golf ball and the like, and thread wound golf balls. Recently, the two-piece golf ball and three-piece golf ball, of which flight distance can be improved while maintaining soft and good shot feel at the time of hitting as good as the conventional thread wound golf ball, generally occupy the greater part of the golf ball market. Multi-piece golf balls represented by the three-piece golf ball have good shot feel while maintaining excellent flight performance, because they can vary hardness distribution, when compared with the two-piece golf ball (Japanese Patent Kokai publication Nos. 80505/1998, 174728/1998 and the like).
In Japanese Patent Kokai publication No. 80505/1998, a golf ball comprising a core, an intermediate layer and a cover, of which the intermediate layer is formed from resin component comprising as a main component a mixture consisted of
10 to 60 parts by weight of thermoplastic elastomer comprising crystalline polyethylene block, and
90 to 40 parts by weight of ionomer resin having a melt index at 190xc2x0 C. of 3 g/min, is described. As the thermoplastic elastomer, thermoplastic elastomer comprising polyethylene block, or polyethylene block and polystyrene block as a hard segment, and ethylene/butylene random copolymer as a soft segment, is described.
In Japanese Patent Kokai publication No. 174728/1998, a multi-piece solid golf ball comprising a core, at least one layer of an intermediate layer and a cover, of which at least one layer of the intermediate layer is formed from as a main component heated mixture of at least two components selected from three components consisting of ionomer resin, thermoplastic elastomer having a terminal OH group, and styrene-butadiene-styrene block copolymer or styrene-isoprene-styrene block copolymer having an epoxy group, and the intermediate layer has a hardness in JIS-C hardness of 40 to 80, and a hardness difference from the center to the surface of the core is not more than 15, is described.
However, in the both golf balls, there is much room for improvement of flight performance, because particularly sufficient rebound characteristics are not obtained. Therefore, it is required to provide a golf ball having better shot feel, better flight performance and better durability.
A main object of the present invention is to provide a multi-piece solid golf ball having very good shot feel, excellent durability and excellent flight performance.
According to the present invention, the object described above has been accomplished by providing a multi-piece solid golf ball comprising a core, an inner cover and an outer cover, employing a blend of ionomer resin and specified thermoplastic elastomer formed from a polymer alloy of an olefin with a block copolymer having styrene block in the inner cover, and adjusting the hardness of the inner cover and outer cover, and the hardness distribution between them to specified ranges, thereby providing a multi-piece solid golf ball having very good shot feel, excellent durability and excellent flight performance.
This object as well as other objects and advantages of the present invention will become apparent to those skilled in the art from the following description with reference to the accompanying drawings.